<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>capture screen</title>
</head>
<body>
<video id="video" controls="controls">
    <source src="http://yningw.oss-cn-shanghai.aliyuncs.com/upload/video/20180503/1525308824389039983.mp4">
</video>
<div id="output"></div>
<script type="text/javascript">
    (function(){
        var video, output;
        var scale = 0.3;
        var initialize = function() {
            output = document.getElementById("output");
            video = document.getElementById("video");
            video.addEventListener('click',captureImage);
        };

        var captureImage = function() {
            var canvas = document.createElement("canvas");
            canvas.width = video.videoWidth * scale;
            canvas.height = video.videoHeight * scale;
            canvas.getContext('2d').drawImage(video, 0, 0, canvas.width, canvas.height);

            var img = document.createElement("img");
            img.src = canvas.toDataURL("image/png");
            output.appendChild(img);
        };

        initialize();
    })();
</script>
</body>
</html>